netSocketCreatePair

fn netSocketCreatePair(
    userdata: ?*anyopaque,
    options: net.Socket.CreatePairOptions,
) net.Socket.CreatePairError![2]net.Socket {
    const t: *Threaded = @ptrCast(@alignCast(userdata));
    _ = t;
    if (!have_networking) return error.OperationUnsupported;
    if (@TypeOf(posix.system.socketpair) == void) return error.OperationUnsupported;
    if (native_os == .haiku) @panic("TODO");

    const family: posix.sa_family_t = switch (options.family) {
        .ip4 => posix.AF.INET,
        .ip6 => posix.AF.INET6,
    };
    const mode, const protocol = try posixSocketModeProtocol(family, options.mode, options.protocol);
    const flags: u32 = mode | if (socket_flags_unsupported) 0 else posix.SOCK.CLOEXEC;

    var sockets: [2]posix.socket_t = undefined;
    const syscall: Syscall = try .start();
    while (true) switch (posix.errno(posix.system.socketpair(family, flags, protocol, &sockets))) {
        .SUCCESS => {
            syscall.finish();
            errdefer {
                closeFd(sockets[0]);
                closeFd(sockets[1]);
            }
            if (socket_flags_unsupported) {
                try setCloexec(sockets[0]);
                try setCloexec(sockets[1]);
            }
            var storages: [2]PosixAddress = undefined;
            var addr_lens: [2]posix.socklen_t = .{ @sizeOf(PosixAddress), @sizeOf(PosixAddress) };
            try posixGetSockName(sockets[0], &storages[0].any, &addr_lens[0]);
            try posixGetSockName(sockets[1], &storages[1].any, &addr_lens[1]);
            return .{
                .{ .handle = sockets[0], .address = addressFromPosix(&storages[0]) },
                .{ .handle = sockets[1], .address = addressFromPosix(&storages[1]) },
            };
        },
        .INTR => {
            try syscall.checkCancel();
            continue;
        },
        .ACCES => return syscall.fail(error.AccessDenied),
        .AFNOSUPPORT => return syscall.fail(error.AddressFamilyUnsupported),
        .INVAL => return syscall.fail(error.ProtocolUnsupportedBySystem),
        .MFILE => return syscall.fail(error.ProcessFdQuotaExceeded),
        .NFILE => return syscall.fail(error.SystemFdQuotaExceeded),
        .NOBUFS => return syscall.fail(error.SystemResources),
        .NOMEM => return syscall.fail(error.SystemResources),
        .PROTONOSUPPORT => return syscall.fail(error.ProtocolUnsupportedByAddressFamily),
        .PROTOTYPE => return syscall.fail(error.SocketModeUnsupported),
        else => |err| return syscall.unexpectedErrno(err),
    };
}